1. Field of the Invention
The present invention relates to a semiconductor device, and more particularly, to a metal oxide semiconductor (MOS) transistor and a manufacturing method thereof.
2. Description of the Related Art
A related art metal oxide semiconductor (MOS) transistor will be described with reference to FIG. 1.
FIG. 1 is a cross-sectional view of a related art MOS transistor 100.
In general, according to a process of forming an NMOS transistor, an oxide such as a shallow trench isolation (STI) 20 is formed in a p-type substrate 10 to isolate devices from each other, and then an impurity is implanted so as to form a well 30. A thin gate oxide layer 40 is formed on the substrate 10 in which the well 30 is formed. Thereafter, polysilicon is deposited on the resultant structure, and then is etched to form a gate 50. Thereafter, an impurity is implanted again into the substrate 10 on both sides of the gate 50 so as to form a source region 60 and a drain region 70, respectively.
The related art MOS transistor 100 is configured such that a channel is formed by applying a predetermined voltage to the gate 50, and a driving current flows by applying a certain voltage to the drain region 40.
Meanwhile, the related art MOS transistor 100 is manufactured of a silicon wafer in hundreds of micrometers thick. However, a portion of the silicon wafer used as a semiconductor device is only a region in tens of micrometers or less deep from the top surface thereof, whereas the other region is used as only the substrate for supporting the semiconductor device.
However, due to the region of the substrate for supporting the semiconductor device, which is referred to as the region for a support substrate in brief, an excessive power is consumed. Moreover, due to a parasitic effect, e.g., the driving speed of the semiconductor device being degraded, caused by the region for the support substrate, there is such a serious problem that it becomes an obstacle to the function of the semiconductor device in the long run.